Precise placement of thioester bonds into sequence-controlled polymers containing ABAC-type units.

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Materials Science

Background:

• Precise placement of thioester bonds in sequence-controlled polymers is a significant challenge.
• Existing methods may lack versatility or require specific catalysts.

Purpose of the Study:

• To demonstrate a versatile, metal-free synthesis of sequence-controlled polymers incorporating thioester bonds.
• To explore the scope and properties of the resulting polymer library.

Main Methods:

• Step polymerization of cyclic thioanhydrides (A), diacrylates (B), and diols/diamines (C).
• Utilized density functional theory (DFT) to understand chemoselectivity.
• Characterized polymer properties including thermal and mechanical performance.

Main Results:

• Synthesized 107 unique polymers with high yields (>90%) and molecular weights up to 175.4 kDa.
• Achieved precise ABAC-type repeating units with distributed thioester, ester, and amide groups.
• Demonstrated tunable properties: glass-transition temperatures (-36-72°C), melting temperatures (43-133°C), degradability, and thermoplastic/elastomeric behavior.

Conclusions:

• Developed a facile, catalyst-free, and atom-economical method for sequence-controlled polymer synthesis.
• The polymer library exhibits tunable performance, highlighting the utility of precisely incorporated thioester bonds.
• This approach offers a new pathway for designing functional polymers with tailored characteristics.